Genny 2/3 s-video mod

ok, I just modded my genesis 3 for s-video, just to see if it works.. and it does.

this will only work for genesis 3 and newer model 2 genesis. it's not possible on model 1 and earlier model 2.

open up the system and locate the chip "Sony CXA 1645/M". it's a 24 pin chip.

you need:

- wire (duh)

- a s-video socket

- 2 75 ohm resistors

- the usual soldering equipment

connect pin 15 of the 1645 to a 75 ohm resistor, and the resistor to the Chrominance pin on the socket. connect pin 16 to the Luminance pin, also with a resistor. connect GND of the socket to pin 1 on the 1645.

if you get no picture or weird green lines, try swapping the C and Y pins.

the hardest part is actually attaching the damn socket to the case. plenty of hotglue will help.. and watch the space, there's very little in a genny 3. I suggest the right side, not the back as I used.. I had to, since my right side already has a 50/60 Hz switch and a headphone socket.


Damn you are the man... I wish I had mad electronic skills...otherwise I would attempt stuff like this. I wouldn't be surprised if you came out with a vga port for the genesis..hehehe..jk.

heh, no.. not gonna happen. the parts are too expensive, and there's alot more involved than just hooking up some wires.
How can you tell if your genny 2 works or not? Does this give is a lot clearer picture? Can this be done with a Sega CD? Thanks a bunch.
if it has a CXA 1645, it works.

the pic is ALOT better than the AV pic.

the mod can't be done to a segacd cause the segacd has no video output at all.
does the Sega CD's video out depend on what hte genesis outputs? So therefore if my Genny 2 was modded to output S-Video then my SCD would output it also?
does the Sega CD's video out depend on what hte genesis outputs?


So therefore if my Genny 2 was modded to output S-Video then my SCD would output it also?

Nope, because (as Arakon already said) SCD doesn't output video of any kind. If you mean "would it work for SCD games", then the answer is probably: Yep.

How do I know if I have a CXA 1645?

Open up your Genesis. Look for a chip near the RF modulator or the A/V output port marked "CXA1645".

And what is that?

A video encoder. It takes the RGB (the signal format everyone would be using if TV's development wasn't so intertwined with broadcasting limitations) output from the video processor and converts it to inferior formats for display on television sets.

That too.
Hey Arakon I have a question.

That S-Video mod looks pretty cool, can this be done to a 32X also?

You didn't say that it wouldn't work, so I thought I would ask
To find out if a Genesis 2 has a CXA-1645 without having to open it up (this might be handy if you're shopping for one!):

1) Model number. If the model number is MK-1451, it definitely has a CXA-1645. (If the model number is MK-16xx, it may or may not have one.)

2) Look through the vents underneath the console, to see the metal RF shielding. If the metal shielding goes all of the way across the vents, it's an older circuit board without a CXA-1645. If the shielding only goes 3/4 of the way across, it's the newer, CXA-1645 equipped board.

So my SCD games would have better output if the genny was modded too? Anyone here have a 32x that will open it up and see if this can be done? Thanks.
it IS possible, but you need an additional circuit. the 1145 in the genny 1 outputs s-video, but needs a timing circuit for it to be usable.
I got an email back from the guy. I will be attempting a mod to one of my model 1's tonight, and then post back here if it worked.
Sweet, keep us informed w/ pics and such. A question: What mods are needed to play all games from all regions on a model 2 genny? Just a US/JAP/PAL switch and a english/japanese switch? Do I also need a 50/60 hrz switch thing? Thanks, appreciate it. Later.
here goes.

you need:

1 s-video socket

1 220 uf capacitor (axial or radial doesn't matter)

1 100 uf capacitor

1 75 ohm resistor

3 pieces of wire

the Sony CXA 1145 is located below the heatsink close to the AV port. be careful when removing that one, the screws are damn tight.

locate pins 15+16. the spot in the top left of the chip marks pin 1.

if neccessary, bend the caps nearby CAREFULLY out of the way.

Connect the + side (unmarked, usually only the - side has a large - sign above the pin on the cap) of the 220 uf cap to pin 16 of the chip. be carefuly that you don't touch the other caps too long. now solder one end of the resistor to the - pin of the 220 uf cap, and a wire to the other end of the resistor.

now connect the + side of the 100 uf cap to pin 15 of the chip. attach a wire to the - side.

solder the 3rd wire to pin 1 or 24 of the chip now.

I recommend bending the caps so they lie flat on the chip, WITHOUT touching any other components or each other on any blank parts. I also highly recommend using a bit of hotglue to keep them in place. if you don't have a hotglue gun, use some tape.

now connect the wires to the s-video socket. if you don't get any pic or a distorted pic, try swapping the C and Y pins on the socket.

that's it.

I suggest attaching the socket behind the cart slot, there's plenty of space there.

this mod also should work the very same way on the model 2 genesis with 1145 instead of 1645, and also the SMS as it uses the same encoder.



thanks to M. Ross for the info!